Highlight dates closer than 3 months away - office-scripts

Question

I have a simple spreadsheet listing certificates and expiry dates. Before we moved this to sharepoint online we had a macro than on opening the spreadsheet would check dates in a range of cells and highlight those within three months. It was intended to highlight anything up for renewal before it expired.
I appreciate macros are not an option in Excel online. Can this (or something very similar) be achieved in Office Scripting?

Answer 1

It should be possible to create an Office Script that highlights cells with a date that is within three months of the present.
Something Like:
function main(workbook: ExcelScript.Workbook)
{
// highlight all days between today and the next number of days out
// Number of days to look ahead
const daysOut = 90;
// Excel by default stores dates as the number of days after January 1, 1900
const dayMin = currentDaysSince1900();
const dayMax = dayMin + daysOut;
// Need to target the column to look at and how far down the column
const columnToLookAt = "A";
const rowStart = 1;
const rowEnd = 4;
const rangeAddress = `${columnToLookAt}${rowStart}:${columnToLookAt}${rowEnd}`;
const sheet = workbook.getActiveWorksheet();
// get range column
const range = sheet.getRange("A1:A3");
const values = range.getValues();
// iterate through the rows of values
for (let i =0 ; i < values.length; i++) {
const value = values[i][0];
console.log(value);
if (typeof value === "number") {
// only look at numbers
if (value >= dayMin && value <=dayMax ) {
// highlight
const rangeAddress = `${columnToLookAt}${rowStart +i}`;
const range = sheet.getRange(rangeAddress);
range.getFormat().getFill().setColor("yellow");
}
}
}
}
/**
* Current Days since Jan 1 1900
* Equivalent to number of current excel day
*/
function currentDaysSince1900() {
// method returns the number of milliseconds elapsed since January 1, 1970
const nowMilliseconds = Date.now();
const millisecondsPerDay = 24 * 60 * 60 * 1000 ;
const nowDays = Math.floor(nowMilliseconds / millisecondsPerDay);
const daysBetween1900And1970 = 25567;
const elapsed = nowDays + daysBetween1900And1970 +2; // add two to include both jan 1s
return elapsed;
}
In terms of triggering the script:
Office Script does not currently support running a script on opening a workbook.
You can manually trigger the script whenever you like.
You can also create a Microsoft Power Automate flow to run the script every day to keep the workbook updated.
More Office Script resources:
Official Microsoft Office Script Date Example
Official Microsoft Office Script Examples
wandyezj office script examples